This invention relates generally to automatic transmission fluid exchange systems and is more particularly directed to system and method of use for replacing the fluid in automatic transmissions having sealed, or inaccessible hydraulic torque converters and which include a fluid circulating pump and inlet and outlet ports for circulation of the hydraulic transmission fluid to fluid coolers and the like.
The following is a list of prior art encountered in the course of a search of the prior art with which my invention is concerned.
Of the above references, some of which pertain to other activities involving the addition or removal of fluid from various and sundry mechanisms, the Becnel U.S. Pat. No. 3,513,941 for FLUID CHANGE MEANS FOR AUTOMATIC TRANSMISSIONS and the DiMatteo U.S. Pat. No. 4,745,989 for VALVE FOR DRAINING AUTOMATIC TRANSMISSION FLUID AND METHOD OF USING SAME are believed to be the most directly pertinent to my invention. In Becnel and DiMatteo, a method and apparatus are described for draining and refilling the fluid in a motor vehicle automatic transmission. The similarities between Becnel and DiMatteo are almost surprising in that each of them provides a cooler outlet and some arrangement for adding fluid to the transmission either through the filler port or to a return line from the transmission fluid cooler. When a transmission cooler line is opened and drained with no restriction the rate of flow at which the fluid is exhausted rapidly increases and fluid is pumped out of the transmission and torque converter much faster than it can be replaced by being pumped in the return line as specified in Becnel""s invention, resulting in a disruption of the usual internal and external fluid flow rates and flow patterns which occur normally; this disruption includes an intermittent, recurrent starvation condition to certain internal transmission components resulting in undue stress and frequent damage to those components. Becnel""s invention appears to have the capability to supply fresh fluid into the transmission through the return line from the cooler back to the transmission at a predetermined, pre-selected flow rate, but his invention allowed no clear means of balancing and/or matching that flow rate to the rate at which fluid is normally circulated through the cooler line back to the transmission or regulating the exhausting of aged fluid into the waste receptacle to produce a balanced substitution of fresh fluid for aged fluid.
Exhausting aged fluid through an open, unrestricted transmission cooler line results in a flow rate to and out of that opening which is far in excess of the rate at which fluid is normally circulated through the cooler, because the usual and significant flow resistance provided by the return line to the transmission itself and the internal down-line components has been eliminated by interrupting/opening the transmission cooler line.
DiMatteo""s invention specifies an unrestricted exhausting of aged fluid through an open cooler line as Becnel""s does and also results in a great increase in rate of flow of fluid through the line leading from the transmission to the cooler line at the point it is exhausted, much greater than normally occurring with a closed cooler line in normal closed-loop circulation. Not only does this result in emptying of the transmission pan and starvation of the internal pump(s) and torque converter as well as other internal components, but Dimatteo""s invention does not specify any pumping of fresh fluid in the return line to the transmission thus, completely disrupting internal and external flow rates and flow patterns and resulting in complete lack of lubrication to the bearings and internal parts of the transmission which receive fluid from the line returning from the cooler to the transmission. DiMatteo specifies adding fresh fluid as the aged fluid when drained out of the open, unrestricted transmission cooler line, by manually pouring it through the filler tube with a poorly metered, poorly controlled method not balanced to rate of exhaust flow.
In the course of arriving at the method and apparatus of my invention, the concepts present in Becnel and DiMatteo were utilized in a similar manner and it was discovered that most, if not all, of the transmissions operated upon became excessively hot or were subject to internal damage to the fluid seals, rear bearings, or other internal components because it was impossible to maintain equality between the fluid added and the fluid drained, because it was impossible to maintain normal fluid flow rates and flow patterns external to and internal within the transmission and its component parts. In other words, what is lacking in Becnel or DiMatteo is a realistic, functional, reliable means or a method for maintaining a balance to provide a dynamic equality of fluid added and fluid removed by replacing aged fluid with fresh fluid through an opened transmission cooler line without disrupting normal internal and external flow rates and flow distribution patterns.
It may be noted that in the event fluid is allowed to drain faster than the rate of addition of fluid, the pump or torque converter in a transmission is likely to be starved and then will become excessively hot under which conditions a transmission will self-destruct if permitted to continue in operation. On the other hand, should excessive fluid be added to build up an internal pressure within the transmission, there is a strong likelihood that seals for shafts and/or valves, bearings, or the like or other internal components, within the transmission, may be irreparably damaged with a resulting failure of the transmission under subsequent operating conditions.
The remainder of the patents are understood to be directed to various and sundry arrangements for adding, removing and changing fluid which are believed to be more remotely related to the concepts of my invention as will be explained in more detail below.
Briefly, my invention is comprised of a fluid receiver for used fluid, a source of supply of fresh fluid, and a means for coordinating the introduction of fresh fluid with the draining of used fluid. With this in mind, it then only remains necessary to separate the fluid flow in a line that is external from the transmission so that the used fluid is drained into a suitable fluid container and the new fluid is introduced at the same rate that the used fluid exits. This can be accomplished in a number of ways, some of which will be described in more detail below.
In one embodiment of my invention, a tank having one port at each end is divided into two chambers by a flexible diaphragm. The tank is filled with fresh fluid through one port which may be known as the supply port and the diaphragm is distended so that substantially the entire tank may be filled with fresh fluid. The supply port, is then connected to the return line of a transmission, the fluid of which is to be renewed. The other port is connected to a drain or exhaust line and the transmission is rendered operative and under these conditions, fluid will be driven from the transmission to the drain line through the drain port of the tank to exert a pressure therein on the diaphragm which will then cause the supply of fresh fluid to flow into the return line and thence back into the transmission. It may now be abundantly clear that the fluid removed is exactly equal to the fluid added so that the transmission will be completely filled with fluid without any excessive pressure drops across sealed shafts or valves and will remain operative in its normal manner with the usual flow rates and flow distribution patterns external to and internally within the transmission and its component parts.
In a typical replacing operation, the fluid drained may be visually observed until the appearance or color assumes that of fresh fluid and the operator will then know that the fluid within the transmission consists essentially, entirely of fresh fluid having the required lubricating and additive properties.
Typically, an amount of fresh fluid in excess of the fluid capacity of a transmission is necessary because of the dilution factor which may vary from transmission to transmission but which is always present. This may vary from 25 to 75 percent of the capacity of a transmission.
In another embodiment of my invention, a pneumatic cushion is provided intermediate individual receptacles for receiving used fluid and adding new fluid while pressure within the receptacles is maintained at a predetermined level commensurate with the normal operating pressure of the fluid in a given transmission.
In a further embodiment of my invention, the apparatus for draining used fluid is provided with a suitable restriction for permitting or controlling the discharge of used fluid so as to maintain, in effect, a back pressure on the circulation pump in a transmission so that the fluid removed by the draining procedure does not exceed the internal source of supply for the pump, which is being replaced at a level consistent with the volume of fluid that is drained. The fresh, clean fluid that is returned to the transmission is then supplied at a rate which is equal to or greater than the volume of expended, dirty fluid that is drained at a controlled rate. A controller, such as is described in one of the illustrated embodiments may be utilized for this purpose.
In another embodiment, an apparatus according to the present invention utilizes an external pump to assist in the extraction of fluid from an access automatic transmission circuit. In another embodiment, an external pumping system introduces for fresh fluid is quite novel when compared to all other prior art since it is bifurcated into two separate but coordinated sources of introducing fresh fluid into the transmission. These two separate but coordinated supply sources can be used to introduce fresh fluid into the transmission at two separate loci at any overall rate needed to match the unrestricted or enhanced exhausting of used fluid specified in the second preferred embodiment.
The invention introduces fresh fluid into the transmission through the cooling return line and this is used in both of its two embodiments during both the static part of the complete fluid exchange and during the dynamic part as well. The invention introduces fresh fluid directly into the transmission pan through the dipstick/filler tube by means of the pan access tube during the static part of the complete fluid exchange in the second embodiment, and during the dynamic part of the complete fluid exchange in the second embodiment. The fresh fluid introduced into the transmission from both sources is metered together, that is, measured additively, and both are suitably regulated individually and together by utilizing a variable flow regulator valve and an adjustable relief valve used as a distribution proportioning valve. Of course many other equivalent means can be used without departing from the art.
In order to maintain overall balance between the rate at which used fluid is extracted and the rate at which fresh fluid is introduced during the dynamic part of the complete fluid exchange, fresh fluid must enter the transmission just as fast as the used fluid flows out of the opened cooling line which has had additional low pressure applied to its cooling outlet side in the second, preferred embodiment.
Lack of inclusion of additional illustrations of embodiments clearly related to and based on this novel art, should not be construed as suggesting that they are not a part of the novel art of this invention.
This invention provides a complete fluid exchange for automatic transmissions consisting, of: 1) the utilization and coordination of a static fluid change which includes flushing, purging, cleaning of the pan and the cooling return line and its downstream circuits; and 2) a dynamic fluid exchange which includes the flushing, purging, cleaning of the remaining inaccessible components such as the torque converter and other internal components which are only accessible with the use of this type of apparatus with the transmission operating.
This invention institutes this complete fluid exchange in as short a period of time as feasible with the least amount of fluid utilized that is practical.
This invention provides the means to unequivocally replace the used fluid extracted during both the static and dynamic phases of the complete fluid exchange in a coordinated, systematically controlled manner.
This invention provides the coordinated means to refill an automatic transmission in as short a time as feasible using the minimum amount of fresh fluid practical without creating any fluid starvation or other potentially harmful conditions in the transmission or vehicle during the dynamic part of the complete fluid exchange.
Because the complete fluid exchange system utilizes enigmatic, unobvious and novel art to attain these utilitarian and commercially useful results, it is therefore distinctly patentable. Each of the two embodiments of the invention specified in FIGS. 8 and 9 incorporate the use of a unique pan access tube, which serves as a used fluid extraction means in both embodiments during the static phase of the complete fluid exchange. It also serves with a second, dual use as an additional, coordinated means of fresh fluid introduction at a second locus during the dynamic phase of the complete fluid exchange in the second preferred embodiment.
The invention provides an apparatus comprised of but not limited to: a source of fresh fluid and means to apply pressure to introduce that fresh fluid into the transmission at more than one locus; a reservoir to receive used fluid extracted from the transmission at more than one locus; a means to apply low pressure to these extraction loci such that used fluid is extracted from them; a means to measure and balance the flow rate and volume of fresh fluid introduced into the transmission and during the dynamic part of the fluid exchange the flow rate and volume of used fluid extracted from the transmission such that fresh fluid is simultaneously exchanged with used fluid at the same approximate rate without causing any starvation conditions or other potentially harmful conditions in any internal transmission component during the dynamic part of the complete fluid exchange when the transmission is running, or during the static part of the complete fluid exchange before the dynamic part of the exchange is instituted.
In summary, the invention has the capability to institute a complete exchange of fresh fluid for used fluid in the shortest time practical using the minimum amount of fresh fluid. It also has the capability of maintaining a balanced rate of flow between the fresh fluid being introduced and the used fluid being extracted. It has the capability to institute virtually a complete flushing and purging of used fluid with an essentially complete cleaning of the transmission. It also provides the operator with an easy to operate apparatus which can be used conveniently to attain the desired results which the complete fluid exchange offers. These novel contributions to the art of changing fluid in automatic transmissions make the invention commercially useful and patentable.
Further objects and advantages of my invention will become apparent from a consideration of the drawings and ensuing description of each.